GB179081A - New or improved instructional device for facilitating explanation of the construction and winding of electric armatures and demonstration of the effects of wrong connections and errors in manufacture - Google Patents

Abstract

179,081. Brook, C. B. May 13, 1921. Teaching electricity.-A device is provided for demonstrating the construction and winding of electric armatures and the effects of short-circuits &c. The device comprises a flat disc d rotatably mounted upon a fixed spindle c attached to a brush-rocker device e of insulating-material, provided with radially extending arms having contact plates upon their underside to represent brushes, which bear against metallic blocks f on the rotating disc acting as commutator segments to carry current to covered flexible wires i, i<1> connected to the terminals of lamp-holders h around the circumference of the disc. The flexible wires are held by two circumferentially spaced series of clips g, g<1>, the two series being at a suitable distance apart in radial alignment and representing the slots of a plate of a drum armature. The wires are preferably of different colours to represent the two portions of a coil passing through each slot, and are provided with removable plugs fitting into sockets in the commutator blocks to illustrate different methods of winding. The contact blocks of the brush-rocker device are provided with means of cross connection by short wires k, and with wires l leading to a source of electrical supply. The spindle is fixed upon a board or plate a having representations of pole-pieces painted or otherwise applied in the requisite positions.. A switch m can be mounted on the board and included in the supply circuit. In a modification the device is constructed to represent a motor or generator, having the wires representing the coils disposed within the armature slots and connected to lamp-holders on a disc supported on the armature shaft at the end remote from the commutator.